Development of Protective Immunity against Inactivated Iranian Isolate of Foot-and-Mouth Disease Virus Type O/IRN/2007 Using Gamma Ray-Irradiated Vaccine on BALB/c Mice and Guinea Pigs

Improved Whole Gamma Irradiated Avian Influenza Subtype H9N2 Virus Vaccine Using Trehalose and Optimization of Vaccination Regime on Broiler Chicken

Gamma (γ)-radiation can target viral genome replication and preserve viral structural proteins compared to formalin inactivation. Thus, a stronger immunity could be induced after the inoculation of the irradiated virus. In this study, γ-irradiated low-pathogenic avian influenza virus-H9N2 (LPAIV-H9N2) was used to immunize the broiler chicken in two formulations, including γ-irradiated LPAIV-H9N2 with 20% Trehalose intranasally (IVT.IN) or γ-irradiated LPAIV-H9N2 plus Montanide oil adjuvant ISA70 subcutaneously (IV+ISA.SC) in comparison with formalin-inactivated LPAIV-H9N2 vaccine intranasally (FV.IN) or formalin-inactivated LPAIV-H9N2 plus ISA70 subcutaneously (FV+ISA.SC). Two vaccination regimes were employed; the first one was primed on day 1 and boosted on day 15 (early regime), and the second one was primed on day 11 and boosted on day 25 (late regime). A challenge test was performed with a live homologous subtype virus. Virus shedding was monitored by quantifying the viral load via RT-qPCR on tracheal and cloacal swabs. Hemagglutination inhibition (HI) antibody titration and stimulation index (SI) of the splenic lymphocyte proliferation were measured, respectively, by HI test and Cell Proliferation assay. Cytokine assay was conducted by the RT-qPCR on antigen-stimulated spleen cells. The results of the HI test showed significant increases in antibody titer in all vaccinated groups, but it was more evident in the IVT late vaccination regime, reaching 5.33 log₂. The proliferation of stimulated spleen lymphocytes was upregulated more in the IVT.IN vaccine compared to other vaccines. The mRNA transcription levels of T-helper type 1 cytokines such as interferon-gamma (IFN-γ) and interleukin 2 (IL-2) were upregulated in all vaccinated groups at the late regime. Moreover, IL-6, a pro-inflammatory cytokine was upregulated as well. However, upregulation was more noticeable in the early vaccination than the late vaccination (p< 0.05). After the challenge, the monitoring of virus shedding for the H9 gene represented an extremely low viral load. The body weight loss was not significant (p > 0.05) among the vaccinated groups. In addition, the viral load of <10^0.5 TCID₅₀/ml in the vaccinated chicken indicated the protective response for all the vaccines. Accordingly, the IVT vaccine is a good candidate for the immunization of broiler chicken via the intranasal route at late regime.

Evaluation of room temperature (30°C to 35°C) lyophilized vaccine with radio inactivated Mannheimia haemolytica whole cells isolated from infected sheep

Background and Aim

Vaccines are one of the important tools for fighting diseases and limiting their spread. The development of vaccines with high efficacy against diseases is essential. Ionizing radiation is the method used for the preparation of the irradiated gamma Mannheimia haemolytica vaccine. The study aimed to measure the metabolic activity and electron microscopic examination of the irradiated bacterial cells and immunological efficiency of different preparations of the irradiated M. haemolytica vaccine.

Materials and Methods

The irradiated vaccines were prepared in three forms at a dose of 2×109 colony-forming unit (CFU) (irradiated M. haemolytica, trehalose irradiated M. haemolytica, and trehalose lyophilized irradiated M. haemolytica). The formalin-killed vaccine was prepared at a dose of 2×109 CFU. Scanning electron microscopy was used to determine the difference between the non-irradiated bacterial cells and the bacterial cells exposed to gamma radiation. The metabolic activity of the irradiated bacterial cells was measured using the Alamar blue technique. Rabbits were divided into five groups (control, vaccinated groups with the formalin-killed vaccine, irradiated bacterial cells without trehalose, trehalose irradiated bacteria, and trehalose lyophilized irradiated bacterial cells). The rabbits were subcutaneously inoculated twice in 2-week intervals. Enzyme-linked immunosorbent assay, interferon-gamma (IFNγ), and interleukin 4 (IL4) assays were used to evaluate the vaccines' immunological efficiency in rabbits.

Results

The metabolic activity tests showed that the bacterial cells exposed to gamma radiation at the lowest lethal dose have metabolic activity. The difference in the metabolic activity between preparations of the irradiated bacterial cells varied according to the cell concentration and incubation time. The highest level of metabolic activity was 8 h after incubation in the nutrient broth medium compared with 4 and 18 h. The scanning electron microscopy of irradiated bacterial cells showed a cavity at the bacterial cell center without rupture of the surrounding cell membrane compared to the non-irradiated bacterial cells. The antibody level in the groups vaccinated with the different preparations of the irradiated bacterial cells was high compared with the control and formalin-killed vaccine groups. The level of the IFNγ showed an increase after the second dose in the group vaccinated with irradiated bacterial cells without trehalose compared with the other groups. The IL4 level in the vaccinated groups with the irradiated bacterial cells without trehalose, irradiated bacterial cells with trehalose, and trehalose lyophilized irradiated bacterial cells were at a high level when compared with the formalin-killed vaccinated group and control group after the second inoculation.

Conclusion

The irradiated M. haemolytica vaccine provides a wide range of humoral and cellular immunity. This study showed high immunological efficiency in rabbits inoculated with the irradiated M. haemolytica vaccine that was shown in the high levels of antibodies (IFNγ and IL4) compared with the group treated with the formalin-killed vaccine. The second dose of irradiated M. haemolytica vaccine is an immune booster that gives the irradiated vaccine a long-acting immunological efficiency.

Advances in Irradiated Livestock Vaccine Research and Production Addressing the Unmet Needs for Farmers and Veterinary Services in FAO/IAEA Member States

The Animal Production and Health section (APH) of the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture at the International Atomic Energy Agency has over the last 58 years provided technical and scientific support to more than 100 countries through co-ordinated research activities and technical co-operation projects in peaceful uses of nuclear technologies. A key component of this support has been the development of irradiated vaccines targeting diseases that are endemic to participating countries. APH laboratories has over the last decade developed new techniques and has put in place a framework that allows researchers from participating member states to develop relevant vaccines targeting local diseases while using irradiation as a tool for improving livestock resources.

Immune Response of Gamma-Irradiated Inactivated Bivalent Polio Vaccine Prepared plus Trehalose as a Protein Stabilizer in a Mouse Model

INTRODUCTION

Poliovirus causes paralysis by infecting the nervous system. Currently, 2 types of polio vaccine are given in many countries in polio eradication program including inactivated polio vaccine (IPV) and oral polio vaccine (OPV). Because of OPV-related paralysis, OPV should be replaced by IPV.

METHODS

The aim of this study was to prepare the gamma-irradiated IPV and determine its effectiveness compared with the commercial vaccine (OPV) in the mouse model. The virus titration of OPV was determined and then inactivated by the appropriate dose of gamma radiation into an irradiated vaccine formula. The vaccine was inoculated in BALB/c mice in 2 different formulations of intramuscular injection with 2-week intervals. The level of anti-polio-neutralizing antibody and polio-specific splenocyte proliferation assay were evaluated by collecting the blood samples and spleens of the vaccinated groups with conventional vaccine and irradiated vaccine.

RESULTS

There was a significant increase in the neutralizing antibody titration between all of the vaccinated groups and negative control group (A) (p < 0.05). And it shows that the IPV by gamma irradiation has the highest antibody titration. Also, the increasing of stimulation index value in the B* group, F group, and G group was the most against other groups. Furthermore, the neutralizing anti-serum titer and splenic lymphocyte proliferation assay show humoral and cellular immunity were significantly increased in the irradiated vaccine group as compared with conventional group.

CONCLUSION

According to the results, gamma-irradiated IPV could induce humoral and cellular immunity in vaccinated mouse groups, so the irradiated poliovirus could be recommended as a good candidate vaccine to prevent the transport of poliovirus to the central nervous system and thus protect against paralysis.

Protective cellular and mucosal immune responses following nasal administration of a whole gamma-irradiated influenza A (subtype H1N1) vaccine adjuvanted with interleukin-28B in a mouse model

The use of gamma-irradiated influenza A virus (γ-Flu), retains most of the viral structural antigens, represent a promising option for vaccine development. However, despite the high effectiveness of γ-Flu vaccines, the need to incorporate an adjuvant to improve vaccine-mediated protection seems inevitable. Here, we examined the protective efficacy of an intranasal gamma-irradiated HIN1 vaccine co-administered with a plasmid encoding mouse interleukin-28B (mIL-28B) as a novel adjuvant in BALB/c mice. Animals were immunized intranasally three times at one-week intervals with γ-Flu, alone or in combination with the mIL-28B adjuvant, followed by viral challenge with a high lethal dose (10 LD₅₀) of A/PR/8/34 (H1N1) influenza virus. Virus-specific antibody, cellular and mucosal responses, and the balance of cytokines in the spleen IFN-γ, IL-12, and IL-4) and in lung homogenates (IL-6 and IL-10) were measured by ELISA. The lymphoproliferative activity of restimulated spleen cells was also determined by MTT assay. Furthermore, virus production in the lungs of infected mice was estimated using the Madin-Darby canine kidney (MDCK)/hemagglutination assay (HA). Our data showed that intranasal immunization with adjuvanted γ-Flu vaccine efficiently promoted humoral, cellular, and mucosal immune responses and efficiently decreased lung virus titers, all of which are associated with protection against challenge. This combination also reduced IL-6 and IL-10 levels in lung homogenates. The results suggest that IL-28B can enhance the ability of the vaccine to elicit virus-specific immune responses and could potentially be used as an effective adjuvant.

Reduction of viral load of avian influenza A virus (H9N2) on SPF eggs and cell line by gamma irradiation

Avian influenza A H9N2 viruses are circulating in domestic poultry worldwide. In this research a low-pathogenic AIV H9N2 was multiplied on MDCK cell line and SPF eggs and irradiated by a Nordian gamma cell instrument. Irradiated and non-irradiated AIV samples were titrated by TCID50 and EID50 methods, respectively. Haemagglutinin antigen was analysed by Haemagglutinin test. Infectivi­ty of irradiated virus samples was determined by cell culture and egg inoculation methods. The virus titration decreased as the dose of gamma radiation increased. AIV proliferation on cell culture can be inactivated by gamma irradiation at a lower dose of gamma-ray (20 kGy) than the virus inactivation on embryonated eggs (30 kGy). The safety test showed complete inactivation of AIV on allantoic fluid with gamma-ray doses: 30 kGy and 20 kGy for virus on MDCK cells after four blind cultures.